There has been nothing unlucky about the number 13 when it comes to NCAA Tournament seeding.

Check out any list of tournament upsets, and featured prominently are games that emerged from the 13 verses 4 pairing.

Remember Princeton’s backdoor basket to beat UCLA in 1996, or Bryce Drew’s buzzer beater that gave Valparaiso a victory over Mississippi two years later?

Vermont over Syracuse in 2005, Morehead State over Louisville in 2011 … all No. 13 seeds.

The 13-16 seeds were added when the bracket expanded to 64 teams in 1985, and historically the 13th seed’s success in the opener against a fourth seeded team has fallen into place.

That is, the 13th seed is 28-108 against the No. 4 since 1985. Not as good as the 12th seed, which is 47-89 against the No. 5, but better than the No. 14 seed, which owns a 21-115 record against the No. 3.

The No. 13 seed has provided a flair for the dramatic, however. Kansas State and Kansas are taking note, along with Virginia Tech and Florida State. That’s the fourth line of this year’s bracket.

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The matchups: Kansas State vs. UC Irvine, Kansas vs. Northeastern, Virginia Tech vs. Saint Louis and Florida State vs. Vermont.

A common thread: The four seeds play in power conferences, the Big 12 and ACC. The opponents, with the exception of Saint Louis of the Atlantic-10, are champions or tournament champs of mid to low major conferences.

The basic formula for an upset begins with this class structure and takes on a David verses Goliath tone. Fourth seeded teams are typically schools from power conferences. The 13th seeds often are mid-to-low majors. Those programs don’t have the overall talent or depth of the better seed, not to mention athletic budget.

But they know how to win.

Last season produced two such outcomes. Marshall defeated Wichita State and Buffalo downed Arizona.

After the victory, Bulls coach Nate Oats said he believed his team was just as good as Arizona entering the game but teams like Buffalo rarely get a chance to prove that during the season.

“We were going to get a high major on a neutral floor,” Oats said. “This is what we’ve been waiting for.”

Last year, Oats believed his team was mis-seeded, that Buffalo deserved better than a No. 13. The Mid-American Conference champions got one this year. They’re the sixth seed in the West Region, and in something of a role reversal, will take on the winner of Wednesday’s First Four game between Arizona State and St. John’s. The power conference teams are No. 11 seeds.

Kansas and Kansas State each own a fourth-seed loss in their tournament history. In 2006, the Jayhawks fell to Bradley. In 2013, Kansas State was topped by La Salle.

Oklahoma’s three opening game losses are the most by a fourth seed. Arizona, Vanderbilt, Indiana and UCLA each have lost twice as a No. 4 seed in the opener.

The pairing produced an upset from the outset, when LSU fell to Navy and David Robinson in 1985.

Among other winners over the years: Missouri State, Manhattan, UNC Wilmington, Siena, San Diego and Hawaii. Southern University’s victory over Georgia Tech in 1993 was the crowing achievement in the career coaching legend Ben Jobe.

Upsets occur annually and throughout the bracket. But victories by the No. 13 seeds have provided the tournament with some of its most memorable moments, usually at the expense of a power conference team.

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1985-2018 SEED VS. SEED

No. 1 vs. No. 16 135-1 .993

No. 2 vs. No. 15 128-8 .941

No. 3 vs. No. 14 115-21 .846

No. 4 vs. No. 13 108-28 .794

No. 5 vs. No. 12 89-47 .654

No. 6 vs. No. 11 85-51 .625

No. 7 vs. No. 10 84-52 .618

No. 8 vs. No. 9 68-68 .500

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